It has been well established that metal detectors can identify targets to some degree based upon their physical composition due to the phase characteristics of a receive signal produced when the target object is in the field of an electromagnetic signal. Patents which illustrate target identification based upon phase include U.S. Pat. Nos. 4,334,191 to Podhrasky, 4,700,139 to Podhrasky and 4,507,612 to Payne.
Various metal detectors have been marketed which provide for target selection by operator classification. A representative product of this type is the Model "Eagle II" manufactured by White's Electronics of Sweethome, Oreg. In the operation of this metal detector, the operator can select target characteristics over a range of 1 to 100. This metal detector assigns a response number to targets based upon their electrical characteristics. The operator can program the detector to have selected search numbers which correspond to certain physical characteristics of desired targets. When the White's "Eagle II" detects an object and classifies it with the same number as has been previously selected by the operator, an audio output is produced along with a visual display indicating a match between the operator's programmed selection and the classification of a particular target. The display and operation, however, are principally numerical, with limited word indicators for target type, and the operator must relate particular numbers in the 1 to 100 range for correlation to desired targets.
In view of the desirability of easily classifying targets desired for detection and for indicating the nature of detected targets, there exist a need for a method of operation and a display for a metal detector which makes operation easy and simple for the operator for and provides accurate target classification and response.